A.a shortage of compressor oil
B.warm food in the refrigerator
C.excessive condenser cooling water
D.a shortage of refrigerant
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A.molecular fluid vibration
B.energy losses
C.wide pressure variations
D.mechanical damage to control valves
A.Keeps the refrigerated space cooler
B.Reduces the efficiency of the plant
C.Takes the load off the compressor
D.Has no affect on the system
A.proportional band
B.the error signal
C.the reset signal
D.feedback
A.Dehydrators must be used continuously in a refrigeration system
B.A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hours
C.A thermostatic expansion valve is used to control refrigerated space temperature
D.The liquid receiver functions to collect and remove non- condensable gases
A.Hydraulic
B.Mechanical
C.Pneumatic
D.Electrical
最新試題
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().
If the head pressure of a reciprocating refrigeration compressor is excessive, ().
If the suction pressure at the refrigeration compressor is below normal, the cause can be().
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should ().
Low compressor head pressure in a refrigeration system can be caused by().
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will ().
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by ().
The control mode in which the final control element is moved from one of two flexed positions to the other is known as ().
A pressure drop through the refrigerant liquid line may cause ().
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump ().